Potential-Modulated
Electrochemiluminescence of Carbon Nitride Nanosheets for Dual-Signal
Sensing of Metal Ions
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Abstract
As
an emerging semiconductor, graphite-phase polymeric carbon nitride
(GPPCN) has drawn much attention not only in photocatalysis but also
in optical sensors such as electrochemiluminescence (ECL) sensing of
metal ions. However, when the concentrations of interfering metal
ions are several times higher than that of the target metal ion, it
is almost impossible to distinguish which metal ion changes the ECL
signals in real sample detection. Herein, we report that the dual-ECL
signals could be actuated by different ECL reactions merely from GPPCN
nanosheets at anodic and cathodic potentials, respectively. Interestingly,
the different metal ions exhibited distinct quenching/enhancement
of the ECL signal at different driven potentials, presumably ascribed
to the diversity of energy-level matches between the metal ions and
GPPCN nanosheets and catalytic interactions of the intermediate species
in ECL reactions. On this basis, without any labeling and masking
reagents, the accuracy and reliability of sensors based on the ECL
of GPPCN nanosheets toward metal ions were largely improved; thus,
the false-positive result caused by interferential metal ions could
be effectively avoided. As an example, the proposed GPPCN ECL sensor
with a detection limit of 1.13 nM was successfully applied for the
detection of trace Ni<sup>2+</sup> ion in tap and lake water